Laminated battery

ABSTRACT

The laminated battery disclosed herein includes an electrode body, an outer casing made of a laminated film which accommodates the electrode body, and an electrode terminal. The outer casing has a weld portion in which inner surfaces of the laminated films are stacked and welded together in a peripheral edge of space which accommodates the electrode body. The electrode terminal passes between the laminated films stacked on each other in the weld portion and is inserted into the outer casing, one end of the electrode terminal is electrically connected to the electrode body, and another end of the electrode terminal is exposed to outside of the outer casing. In addition, at least a part of the electrode terminal inserted into the outer casing is plate-shaped. In the plate-shaped portion, a surface-roughened portion having a notch portion is provided at a position of the weld portion.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority based on Japanese PatentApplication No. 2021-046430 filed on Mar. 19, 2021, the entire contentsof which are incorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

The present invention relates to a laminated battery.

2. Description of the Background

Japanese Patent Application Publication No. 2001-93483 discloses aninvention relating to a thin battery bag for accommodating a thinbattery power generation element. In the bag disclosed in JapanesePatent Application Publication No. 2001-93483, in a peripheral edgethereof, a heat seal portion is formed. The heat seal portion ischaracterized in that part of the heat seal portion is formed into anotched shape from an inner edge toward an outer edge such that the sealwidth thereof is narrower than the seal width of other heat sealportions. With this, in the case where the internal pressure of an outercasing abnormally rises, the internal pressure is concentrated on aportion formed into the notched shape. Subsequently, it is assumed thatthe seal portion in the portion is peeled, a vaporized substance in theouter casing is released to the outside, and the sealability of theentire outer casing is reduced relatively slowly.

SUMMARY

In a laminated battery, when pressure inside an outer casing (internalpressure) rises to a predetermined value or higher, it is desirable thatthe outer casing is torn and the internal pressure is thereby releasedmore stably. On the other hand, when the pressure inside the outercasing (internal pressure) is permissible internal pressure, it isdesirable that the outer casing is not torn. In a mode in which thenotch-shaped portion is formed only by adjusting the seal width of theheat seal portion, variation of the internal pressure which causespeeling of the heat seal portion from the notch-shaped portion can beincreased unless the notched shape of the heat seal portion is formedwith high accuracy. Accordingly, when accuracy in the formation of theheat seal portion is low, a phenomenon, in which the heat seal portionis peeled at the permissible internal pressure, or the heat seal portionis not peeled even when the permissible internal pressure is exceeded,easily occurs.

A laminated battery disclosed herein is a laminated battery including:an electrode body; a bag-shaped outer casing made of a laminated filmwhich accommodates the electrode body; and an electrode terminal, andthe outer casing has a weld portion in which inner surfaces of thelaminated films are stacked and welded together in a peripheral edge ofspace which accommodates the electrode body. The electrode terminalpasses between the laminated films stacked on each other in the weldportion and is inserted into the outer casing, one end of the electrodeterminal is electrically connected to the electrode body inside theouter casing, and another end of the electrode terminal is exposed tooutside of the outer casing. In addition, at least a part of theelectrode terminal inserted into the outer casing is plate-shaped, theelectrode terminal has a surface-roughened portion, which has anarithmetic average height higher than an arithmetic average height ofanother part, at a position of the weld portion in the part insertedinto the outer casing, and a notch portion is provided in thesurface-roughened portion.

According to the configuration, the surface-roughened potion having thenotch portion is provided in the portion of the electrode terminal towhich the laminated film is welded. It is possible to adjust the widthof the surface-roughened portion and the shape of the notch portioneasily with high accuracy. Accordingly, adjustment of a predeterminedvalue of internal pressure of the outer casing at which peeling occursin the weld portion of the laminated film is facilitated, and variationof the predetermined value is reduced. As a result, when the pressureinside the outer casing (internal pressure) rises to the predeterminedvalue, it is possible to stably tear the outer casing from the notchportion, and release the internal pressure.

In a preferred aspect of the laminated battery disclosed herein, thenotch portion is provided such that a width of the surface-roughenedportion is partially reduced from an inner side of the outer casingtoward an outer side of the outer casing. By adjusting the partiallyreduced width of the surface-roughened portion, it is possible to adjustthe predetermined value of the internal pressure at which the outercasing is torn.

In a preferred aspect of the laminated battery disclosed herein, thearithmetic average height of the surface-roughened portion is not lessthan 0.1 μm and not more than 30 μm. When the arithmetic average heightfalls within the range, a surface area of a surface to which thelaminated film is welded is increased properly, and hence, even when thenotch portion is provided, it is possible to maintain the bondingstrength of the laminated film at a high level.

In a preferred aspect of the laminated battery disclosed herein, thesurface-roughened portion is entirely covered with the weld portion.With this, it is possible to prevent metal power which thesurface-roughened portion can have from being scattered to the insideand the outside of the outer casing.

In a preferred aspect of the laminated battery disclosed herein, part ofthe surface-roughened portion is exposed to the outside of the outercasing. With this, the surface-roughened portion is disposed in an endportion outside the weld portion, and hence it is possible to weld theelectrode terminal and the outer casing more reliably.

In a preferred aspect of the laminated battery disclosed herein, theelectrode terminal is constituted by a clad material in which the oneend of the electrode terminal is made of a first metal and the other endof the electrode terminal is made of a second metal different from thefirst metal. With this, it is possible to improve bondability to membersconnected to the one end and the other end of the electrode terminal.

In a preferred aspect of the laminated battery disclosed herein, thesurface-roughened portion is provided so as to straddle a boundarybetween the first metal and the second metal. In addition, in apreferred aspect thereof, a boundary between the first metal and thesecond metal is covered with the weld portion. With this, it is possibleto firmly weld the laminated film such that the boundary between thefirst metal and the second metal is covered with the laminated film, andhence it is possible to prevent an electrolyte (e.g., an electrolytesolution) and water in the air from entering the boundary.

In a preferred aspect of the laminated battery disclosed herein, one ofthe first metal and the second metal is made of copper or an alloymainly composed of copper, and a coat layer is provided on a surface ofa portion of the copper or the alloy mainly composed of copper. Withthis, it is possible to prevent contact between the copper or the alloymainly composed of copper and resin (e.g., the inner surface of thelaminated film) and suppress oxidation degradation of the resin.

In a preferred aspect of the laminated battery disclosed herein, thelaminated battery further includes a resin layer between thesurface-roughened portion and the laminated film in the weld portion.With this, it is possible to improve bonding strength between theelectrode terminal and the laminated film.

In a preferred aspect of the laminated battery disclosed herein, atleast part of the resin layer protrudes to the outside of the outercasing. With this, it is possible to insulate the electrode terminalfrom the outer casing more reliably.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view schematically showing a laminated battery 1according to an embodiment;

FIG. 2 is a partially cutaway plan view of the laminated battery 1 inFIG. 1;

FIG. 3 is a cross-sectional view taken along the line of FIG. 1;

FIG. 4 is a plan view schematically showing the configuration of aterminal 100;

FIG. 5 is a partially cutaway plan view schematically showing theconfiguration of the laminated battery 1 including a resin layer 40;

FIG. 6 is a plan view schematically showing the configuration of theterminal 100 according to a first modification;

FIG. 7 is a plan view schematically showing the configuration of theterminal 100 according to a second modification; and

FIG. 8 is a plan view schematically showing the configuration of thelaminated battery 1 according to a third modification.

DETAILED DESCRIPTION

Hereinbelow, a preferred embodiment of a technique disclosed herein willbe described with reference to the drawings appropriately. Note that,apart from matters which are specifically mentioned in the presentspecification, other matters which are necessary for implementation canbe understood as design matters of those skilled in the art based on theconventional art in the field. The technique disclosed herein can beimplemented based on contents disclosed in the present specification andcommon general technical knowledge in the field. In addition, in thefollowing drawings, members and portions which have the same functionsare designated by the same reference numerals, and the duplicatedescription thereof is omitted or simplified in some cases.

Note that, in the present specification, a “laminated battery” denotesbatteries each having a configuration in which an electrode body isaccommodated inside a laminated film (sheet)-shaped outer casing member(outer casing). In addition, in the present specification, a “battery”is a term denoting storage devices from which electrical energy can beextracted, and is a concept including a primary battery and a secondarybattery. Further, in the present specification, a “secondary battery” isa term denoting storage devices which can be charged and dischargedrepeatedly, and is a concept including what is called a storage battery(chemical cell) such as a lithium ion secondary battery or anickel-metal hydride battery, and a capacitor (physical cell) such as anelectric double layer capacitor.

FIG. 1 is a plan view schematically showing a laminated battery 1according to an embodiment. FIG. 2 is a partially cutaway plan view ofthe laminated battery 1 in FIG. 1. FIG. 3 is a cross-sectional viewtaken along the line of FIG. 1. As shown in FIG. 1 and FIG. 2, thelaminated battery 1 includes an outer casing 10, an electrode body 20,electrode terminals (a positive electrode terminal 32 and a negativeelectrode terminal 34), and an electrolyte (not shown).

Note that, in the following description, it is assumed that referencesigns X, Y, and Z in the drawings indicate a short side direction of thelaminated battery 1, a long side direction thereof orthogonal to theshort side direction, and a thickness direction thereof, respectively.Note that the directions are merely directions for the sake ofconvenience of explanation, and are not intended to limit a placementmode of the laminated battery 1.

The outer casing 10 is typically constituted by a bag-shaped laminatedfilm, and accommodates the electrode body 20 and the electrolyte insidethe outer casing 10. In addition, a weld portion 18 in which innersurfaces (i.e., surfaces facing the electrode body 20) of a laminatedfilm are stacked and welded together is formed in a peripheral edge ofspace of the outer casing 10 which accommodates the electrode body 20and the electrolyte. With this, the electrode body 20 and theelectrolyte are sealed inside the outer casing 10. In the presentembodiment, the outer casing 10 is formed by stacking wide surfaces oftwo rectangular laminated films and heat-welding both end portions inthe short side direction X of the laminated battery 1 and both endportions in the long side direction Y of the laminated battery 1together so as to form a belt-like shape. Note that, in order to formthe outer casing 10, one rectangular laminated film which is doubled ora cylindrical laminated film may also be used. In such a case, it isonly necessary to form the weld portion 18 only in a portion required toseal the outer casing 10, and the weld portion 18 does not need to beformed in the entire peripheral edge portion of the space whichaccommodates the electrode body 20 and the electrolyte. In addition, theouter casing 10 may also be formed by laminating three or more laminatedfilms.

The outer casing 10 has insulation properties and resistance to theelectrolyte to be used. In order to allow heat welding, the outer casing10 has a sealant layer made of resin at least as an inner surface (asurface facing the electrode body 20). In the present embodiment, asshown in FIG. 3, the outer casing 10 has a three-layer structure inwhich a sealant layer 12, a metal layer 14, and a protective layer 16are stacked in this order from an inner side. Note that the structure ofthe outer casing 10 is not limited to the above three-layer structure,and the outer casing 10 may have, e.g., a single layer structure havingonly the sealant layer and may also have a multilayer structure havingtwo layers or four or more layers.

Examples of the resin constituting the sealant layer 12 includethermoplastic resins such as a polyolefin resin, a polyester resin, apolystyrene resin, and a polyvinyl chloride resin. Examples of thepolyolefin resin include polyethylene (PE), polypropylene (PP), andacid-modified polyolefin resins such as maleic anhydride-modifiedpolypropylene and maleic anhydride polyester. An example of thepolyester resin includes polyethylene terephthalate (PET) or the like.In addition, in order to prevent oxidation caused by contact with ametal member (e.g., an electrode terminal), the sealant layer 12 cancontain a metal inactivating agent.

The metal layer 14 is a layer for improving gas barrier properties andmoisture barrier properties of the outer casing 10. The metal layer 14can be made of metal materials such as, e.g., aluminum, iron, andstainless steel. From the viewpoint of reducing cost and weight, amongthe metal materials, the metal layer 14 is preferably made of aluminum.

The protective layer 16 is a layer for improving durability and shockresistance of the outer casing 10. The protective layer 16 is made of,e.g., a biaxially oriented polyester-based resin or a biaxially orientedpolyamide-based resin. An example of the biaxially orientedpolyester-based resin includes biaxially oriented polyethyleneterephthalate or the like. An example of the biaxially orientedpolyamide-based resin includes nylon or the like. Note that theprotective layer 16 typically constitutes an outer surface of the outercasing 10, but another layer may be further provided outside theprotective layer 16 and, e.g., a printed layer or a flame-retardantlayer may be provided.

The configuration of the electrode body 20 may be similar to that of aconventionally known battery, and is not particularly limited. Theelectrode body 20 includes a sheet-shaped positive electrode (positiveelectrode sheet) and a sheet-shaped negative electrode (negativeelectrode sheet). Herein, the electrode body 20 is a laminated electrodebody in which a square (typically, rectangular) positive electrode sheetand a square (typically, rectangular) negative electrode sheet arestacked in a state in which the square positive electrode sheet and thesquare negative electrode sheet are insulated from each other. Note thatthe electrode body 20 may also be, e.g., a wound electrode body in whicha belt-shaped positive electrode sheet and a belt-shaped negativeelectrode sheet are stacked and wound in a longitudinal direction in astate in which the belt-shaped positive electrode sheet and thebelt-shaped negative electrode sheet are insulated from each other.

The positive electrode sheet has positive electrode current collectorfoil and a positive electrode active material layer (not shown) whichcontains a positive electrode active material. The positive electrodeactive material layer is formed on one surface or both surfaces of thepositive electrode current collector foil. In addition, at an endportion of the positive electrode current collector foil (herein, an endportion on the left in the long side direction Y in FIG. 2), a positiveelectrode current collector foil exposed portion 22 in which thepositive electrode active material layer is not formed is provided. Thepositive electrode current collector foil is made of a metal materialsuch as, e.g., aluminum, nickel, titanium, or stainless steel. Thepositive electrode active material may be similar to that of theconventionally known battery, and it is possible to use a lithiumtransition metal composite oxide such as, e.g., alithium-nickel-cobalt-manganese composite oxide.

The negative electrode sheet has negative electrode current collectorfoil and a negative electrode active material layer (not shown) whichcontains a negative electrode active material. The negative electrodeactive material layer is formed on one surface or both surfaces of thenegative electrode current collector foil. In addition, at an endportion of the negative electrode current collector foil (herein, an endportion on the right in the long side direction Y in FIG. 2), a negativeelectrode current collector foil exposed portion 24 in which thenegative electrode active material layer is not formed is provided. Thenegative electrode current collector foil is made of a metal materialsuch as, e.g., copper, nickel, titanium, or stainless steel. Thenegative electrode active material may be similar to that of theconventionally known battery, and it is possible to use a carbonmaterial such as, e.g., graphite.

The electrolyte may be similar to that of the conventionally knownbattery, and is not particularly limited. As the electrolyte, it ispossible to use, e.g., a nonaqueous electrolyte solution containing anonaqueous solvent and a supporting electrolyte. As the nonaqueoussolvent, it is possible to use aprotic solvents such as, e.g.,carbonates, ethers, esters, sulfones, and lactones. As the supportingelectrolyte, it is possible to use lithium salt such as, e.g., LiPF₆.The concentration of the supporting electrolyte is not particularlylimited, and the concentration thereof can be, e.g., 0.1 mol/L to 1.2mol/L. Note that the electrolyte is not limited to a liquid electrolyte,and the electrolyte may be a gel-like electrolyte or may also be a solidelectrolyte.

The electrode terminals (the positive electrode terminal 32 and thenegative electrode terminal 34) pass between the laminated films stackedon each other in the weld portion 18 and are inserted into the outercasing 10. One end of the positive electrode terminal 32 is electricallyconnected to the positive electrode current collector foil exposedportion 22 inside the outer casing 10, and the other end of the positiveelectrode terminal 32 is exposed to the outside of the outer casing 10.The positive electrode terminal 32 is, e.g., a plate-shaped metal memberhaving a rectangular wide surface. The positive electrode terminal 32may be similar to that used in a conventionally known laminated battery,and is made of, e.g., aluminum or an alloy mainly composed of aluminum.One end of the negative electrode terminal 34 is electrically connectedto the negative electrode current collector foil exposed portion 24inside the outer casing 10, and the other end of the negative electrodeterminal 34 is exposed to the outside of the outer casing 10. Thenegative electrode terminal 34 is, e.g., a plate-shaped metal memberhaving a rectangular wide surface. The negative electrode terminal 34may be similar to that used in the conventionally known laminatedbattery, and is made of, e.g., copper or an alloy mainly composed ofcopper. Note that, in the present specification, an “alloy mainlycomposed of a metal M” denotes an alloy having the metal M as aningredient having the highest content (the metal M is any metal).Hereinbelow, a description will be given of the configuration of aterminal (electrode terminal) 100 constituting the negative electrodeterminal 34. Note that the terminal 100 can also be used as the positiveelectrode terminal 32.

FIG. 4 is a plan view schematically showing the configuration of theterminal 100. The terminal 100 has an inner terminal portion 110 at oneend, an outer terminal portion 120 at the other end, and a plate-shapedportion 130 between the inner terminal portion 110 and the outerterminal portion 120. Further, a surface-roughened portion R having anotch portion N is provided on the surface of the plate-shaped portion130. In the present embodiment, the terminal 100 is plate-shaped and hasa rectangular wide surface, and the shape of the wide surface is notparticularly limited. In addition, as long as the terminal 100 has theplate-shaped portion 130, the inner terminal portion 110 and the outerterminal portion 120 do not need to be plate-shaped.

The inner terminal portion 110 is a portion which is connected to theelectrode body 20 inside the outer casing 10. For example, as shown inFIG. 2, the inner terminal portion 110 is directly connected to thenegative electrode current collector foil exposed portion 24 inside theouter casing 10. In addition, the inner terminal portion 110 may beindirectly connected to the electrode body 20 and may be connected tothe electrode body 20 via, e.g., a conductive member.

The outer terminal portion 120 is a portion which is exposed to theoutside of the outer casing 10. For example, as shown in FIG. 2, theterminal 100 is disposed so as to be inserted into the outer casing 10,and the outer terminal portion 120 is thereby disposed outside the outercasing 10. The outer terminal portion 120 is a portion which can beconnected to other members, and can be connected to a conductive metalmember such as, e.g., a bus bar.

The plate-shaped portion 130 has the surface-roughened portion R on thesurface. The surface-roughened portion R is provided in a predeterminedpart to which the laminated film is welded. Protrusions and depressionsare formed in the surface-roughened portion R. Consequently, thesurface-roughened portion R has an arithmetic average height Sa which ishigher than those of the other parts of the terminal 100. With this, thesurface area of the surface-roughened portion R is increased, and hencethe laminated film is welded more firmly.

Protrusions and depressions are formed in the surface-roughened portionR. The arithmetic average height Sa of the surface-roughened portion Ris not particularly limited, and is preferably not less than 0.1 μm andnot more than 30 μm. When the arithmetic average height Sa falls withinthe above range, the surface area of the surface to which the laminatedfilm is welded is suitably increased without spoiling the strength andconductivity of the terminal 100. Consequently, even when the notchportion N described later is provided in the surface-roughened portionR, it is possible to maintain the bonding strength of the laminated filmat a high level. Note that it is possible to measure the arithmeticaverage height Sa by observation with a laser microscope. As the lasermicroscope, it is possible to use, e.g., VK-X1000 manufactured byKEYENCE CORPORATION.

In the vicinity of the tip of a protrusion portion of protrusions anddepressions of the surface-roughened portion R, a minute metal particlecan exist. With this, the surface area of the surface-roughened portionR is further increased, and hence firmer weld to the laminated film isimplemented. The above metal particle is a particle generated by surfaceroughening by laser irradiation or the like. In this case, the metalparticle is made of the same metal material as that of the portion inwhich the surface-roughened portion R is provided. The metal particlecan have an average diameter of, e.g., 50 nm to 1000 nm. It is possibleto observe the metal particle with a scanning electron microscope (SEM).

As shown in FIG. 4, in the present embodiment, the surface-roughenedportion R is provided from one end of the surface of the plate-shapedportion 130 to the other end thereof so as to form a belt-like shape. Inaddition, in the present embodiment, the surface-roughened portion R isprovided on both surfaces of the plate-shaped portion 130. Further, thesurface-roughened portion R is preferably provided on an end surface ofthe plate-shaped portion 130. With this, it is possible to weld thelaminated film and the terminal 100 together more firmly, and improvethe sealability of the outer casing 10. Accordingly, it is possible toprevent the outer casing 10 from being torn from a portion other thanthe notch portion N unexpectedly. Note that the surface-roughenedportion R may also be provided only on one surface of the plate-shapedportion 130.

The notch portion N is provided in the surface-roughened portion R. Asshown in FIG. 4, in the present embodiment, the notch portion N of whichthe width is partially reduced from a side on which the inner terminalportion 110 is provided toward a side on which the outer terminalportion 120 is provided (the direction Y in FIG. 4) is provided in thesurface-roughened portion R. In other words, in the surface-roughenedportion R, the notch portion N of which the width is partially reducedfrom the inner side of the outer casing 10 toward the outer side thereofis provided. In a portion in which the notch portion N is provided, awidth Y2 which is the narrowest width in a width Y1 of thesurface-roughened portion R is present. In the notch portion N, thewidth of the portion subjected to surface roughening is narrower thanthose of the other portions, and hence the width of the portion to whichthe laminated film is welded firmly is reduced. With this, when thepressure inside the outer casing 10 (internal pressure) rises to apredetermined value, the outer casing 10 is torn stably from the notchportion N, and the internal pressure is released. In addition, byadjusting the narrowest width Y2, it is possible to adjust thepredetermined value of the internal pressure of the outer casing 10 atwhich the outer casing 10 is torn. Although not particularly limited,the narrowest width Y2 can be a width of, e.g., ¼ to ¾ of the width Y1of the surface-roughened portion R.

It is possible to provide the surface-roughened portion R byconventionally known methods such as, e.g., laser irradiation, etching,plating treatment (e.g., roughened nickel plating, roughened copperplating, or roughened silver plating), frame treatment, coronatreatment, plasma treatment, and surface polishing. According to thetechnique of surface roughening, it is possible to easily performadjustment of the narrowest width Y2 of the surface-roughened portion Rand adjustment of the shape of the notch portion with high accuracy.With this, variation of the internal pressure of the outer casing 10which causes peeling of the laminated film welded to thesurface-roughened portion R is reduced. As a result, it is possible tostably tear the outer casing 10 at a desired value of the internalpressure of the outer casing 10 from the notch portion N. Note that, asshown in FIG. 4, the shape of the notch portion N is triangular whenviewed in, e.g., a plan view. However, the shape of the notch portion Nis not particularly limited, and can be trapezoidal, semicircular,rhombic, and polygonal.

The number of notch portions N is not particularly limited, and may beone or may also be two or more. In addition, the notch portion N may beprovided only on one surface of the plate-shaped portion 130 and mayalso be provided on both surfaces thereof.

The terminal 100 is made of metal having conductivity, and the metal maybe similar to metal constituting an electrode terminal used in theconventionally known laminated battery. Examples of the metal includealuminum, an alloy mainly composed of aluminum, copper, an alloy mainlycomposed of copper, and nickel. In the present embodiment, the terminal100 is made of copper. Note that the metal constituting the terminal 100may be appropriately changed depending on whether the metal is used inthe positive electrode terminal 32 or the negative electrode terminal34.

In the case where the terminal 100 is made of copper or an alloy mainlycomposed of copper, a coat layer is preferably provided at least at aposition in the plate-shaped portion 130 to which the laminated film iswelded. The sealant layer 12 of the outer casing 10 directly comes intocontact with copper, and oxidation degradation of the resin constitutingthe sealant layer 12 can be thereby facilitated. Accordingly, byproviding the coat layer, it is possible to suppress degradation of thesealant layer 12. The coat layer can be made of, e.g., nickel,molybdenum, zirconium, titanium, a trivalent chromium compound, aphosphorous compound, triazine thiol, or an aminated phenol polymer. Amethod of forming the coat layer may be appropriately changed accordingto the material of the coat layer, and examples of the method includeplating treatment (nickel plating or the like) and solution treatment(phosphate chromate treatment, triazine thiol treatment, or the like).

As shown in FIG. 2 and FIG. 3, in the present embodiment, thesurface-roughened portion R is entirely covered with the weld portion18. That is, herein, the width Y1 of the surface-roughened portion R isnarrower than a width Y3 of the weld portion, and the entiresurface-roughened portion R is welded to the laminated film. With this,it is possible to prevent metal powder (metal particle) generated whenthe surface-roughened portion R is formed from being scattered to theinside and the outside of the outer casing 10.

In the weld portion 18, the laminated battery 1 can include a resinlayer 40 between the surface-roughened portion R of the terminal 100 andthe laminated film. The resin layer 40 is integrated with the sealantlayer 12 of the laminated film by heat welding, and hence it is possibleto strengthen the weld between the terminal 100 and the laminated film.Note that the resin layer 40 can be made of a material which canconstitute the above sealant layer 12.

FIG. 5 is a partially cutaway plan view schematically showing theconfiguration of the laminated battery 1 including the resin layer 40.In the present embodiment, the resin layer 40 covers the entiresurface-roughened portion R. Note that the resin layer 40 may also bedisposed so as to cover only part of the surface-roughened portion R. Inaddition, the resin layer 40 may be provided only on one surface side ofthe terminal 100 and may also be provided on both surface sides thereof.Although not particularly limited, the thickness of the resin layer 40can be, e.g., 50 μm to 250 μm.

In addition, as shown in FIG. 5, the resin layer 40 is preferablydisposed such that at least part of the resin layer 40 protrudes to theoutside of the outer casing 10. With this, it is possible to insulatethe terminal 100 from the outer casing 10 more reliably. Note that theresin layer 40 may be provided only within the width Y3 of the weldportion 18 and may also protrude to the inside of the outer casing 10.

A method of forming the resin layer 40 is not particularly limited, andit is possible to form the resin layer 40 by, e.g., welding afilm-shaped resin (sealant film) to the terminal 100. It is possible tomanufacture the laminated battery 1 including the resin layer 40 byinserting the terminal 100 including the resin layer 40 betweenlaminated films which are stacked on each other and heat-welding thelaminated films. Examples of the other methods of forming the resinlayer 40 include application of a resin material and insert molding.

The laminated battery 1 can be used for various purposes. For example,it is possible to suitably use the laminated battery 1 as a high outputpower source (driving power source) for a motor mounted on a vehicle.The type of the vehicle is not particularly limited, and examples of thevehicle typically include automobiles such as, e.g., a plug-in hybridelectric vehicle (PHEV), a hybrid electric vehicle (HEV), and an batteryelectric vehicle (BEV).

One embodiment of the technique disclosed herein has been described thusfar. Note that the above-described embodiment shows an example of thelaminated battery disclosed herein, and is not intended to limit thetechnique disclosed herein. Hereinbelow, modifications of the techniquedisclosed herein will be described.

First Modification

FIG. 6 is a plan view schematically showing the configuration of theterminal 100 relating to a first modification. While the terminal 100 ismade of one type of a metal in the above-described embodiment, theterminal 100 may also be a clad material in which different types ofmetals are bonded to each other. In the first modification, the innerterminal portion 110 is made of a first metal, and the outer terminalportion 120 is made of a second metal different from the first metal. Aboundary B between the first metal and the second metal is disposed inthe plate-shaped portion 130 in this modification. By using the cladmaterial, it is possible to make the first metal constituting the innerterminal portion 110 identical to a metal constituting a metal member(e.g., the positive electrode current collector foil exposed portion 22,the negative electrode current collector foil exposed portion 24, or thelike) connected to the inner terminal portion 110, and it is possible tomake the second metal constituting the outer terminal portion 120identical to a metal constituting a metal member (e.g., the bus bar orthe like) connected to the outer terminal portion 120. With this,bondability of each of the inner terminal portion 110 and the outerterminal portion 120 to other members is improved.

As the first metal and the second metal, it is possible to use, e.g.,aluminum, an alloy mainly composed of aluminum, copper, an alloy mainlycomposed of copper, and nickel. In the case where one of the first metaland the second metal is made of copper or the alloy mainly composed ofcopper, the above-described coat layer is preferably provided on thesurface of the portion made of copper or the alloy mainly composed ofcopper. The material and formation method of the coat layer may besimilar to those in the above-described embodiment.

In the boundary B between the first metal and the second metal, in thecase where an electrolyte (e.g., an electrolyte solution) enters theboundary B or in the case where water enters the boundary B from theoutside air, electrolytic corrosion may occur. Accordingly, thesurface-roughened portion R is preferably provided so as to straddle theboundary B between the first metal and the second metal. With this, thelaminated film is welded to both of the first metal and the second metalfirmly, and hence it is possible to weld the laminated film such thatthe boundary B between the first metal and the second metal is coveredwith the laminated film. In addition, the notch portion N is preferablyprovided on the surface of the first metal. With this, it is possible toprevent the electrolyte (e.g., the electrolyte solution) from enteringthe boundary B between the first metal and the second metal from thenotch portion N.

Second Modification

FIG. 7 is a plan view schematically showing the configuration of theterminal 100 relating to a second modification. In the above-describedembodiment, the notch portion N is provided by partially reducing thewidth of the surface-roughened portion R from the side on which theinner terminal portion 110 is provided toward the side on which theouter terminal portion 120 is provided (the long side direction Y inFIG. 4), but the notch portion N is not limited thereto. As shown inFIG. 7, the notch portion N which allows the side on which the innerterminal portion 110 is provided and the side on which the outerterminal portion 120 is provided to communicate with each other in aportion of the surface-roughened portion R which is not subjected tosurface roughening may also be provided. With this, when the laminatedfilm is welded to the surface-roughened portion R, the bonding strengthof the portion which is not subjected to surface roughening is reduced.As a result, when the internal pressure of the outer casing 10 rises tothe predetermined value, the laminated film of the portion which is notsubjected to surface roughening is peeled, and the internal pressure canbe thereby released. In addition, it is possible to appropriately adjustthe predetermined value at which the internal pressure of the outercasing 10 is released with the resin layer 40.

Third Modification

FIG. 8 is a plan view schematically showing the configuration of thelaminated battery 1 according to a third modification. In the embodimentdescribed above, the surface-roughened portion R is provided only at theposition of the weld portion 18, but the surface-roughened portion R isnot limited thereto. As shown in FIG. 8, part of the surface-roughenedportion R may be exposed to the outside of the outer casing 10. Withthis, the surface-roughened portion R is disposed in an end portionoutside the weld portion 18, and hence it is possible to weld theterminal 100 and the outer casing 10 more reliably. Note that, in FIG.8, the width Y1 of the surface-roughened portion R is wider than thewidth Y3 of the weld portion 18, but the width Y1 of thesurface-roughened portion R may be narrower than the width Y3 of theweld portion 18 and may also be equal to the width Y3 of the weldportion 18.

Other Modifications

In the embodiment described above, as shown in, e.g., FIG. 1, thepositive electrode terminal 32 extends from one of end portions of theouter casing 10 in the long side direction Y, and the negative electrodeterminal 34 extends from the other end portion thereof in the long sidedirection Y. However, the positive electrode terminal 32 and thenegative electrode terminal 34 are not limited thereto. For example, thepositive electrode terminal 32 and the negative electrode terminal 34may extend together from an end portion of the outer casing 10 in thesame direction, e.g., from one of end portions thereof in the long sidedirection Y. In addition, the terminal 100 may be used as each of thepositive electrode terminal 32 and the negative electrode terminal 34 ofthe laminated battery 1, and may also be used only as one of thepositive electrode terminal 32 and the negative electrode terminal 34thereof

What is claimed is:
 1. A laminated battery comprising: an electrodebody; a bag-shaped outer casing made of a laminated film whichaccommodates the electrode body; and an electrode terminal, wherein theouter casing has a weld portion in which inner surfaces of the laminatedfilms are stacked and welded together in a peripheral edge of spacewhich accommodates the electrode body, the electrode terminal passesbetween the laminated films stacked on each other in the weld portionand is inserted into the outer casing, one end of the electrode terminalis electrically connected to the electrode body inside the outer casingand another end of the electrode terminal is exposed to outside of theouter casing, at least a part of the electrode terminal inserted intothe outer casing is plate-shaped, the electrode terminal has asurface-roughened portion, which has an arithmetic average height higherthan an arithmetic average height of another part, at a position of theweld portion in the part inserted into the outer casing, and a notchportion is provided in the surface-roughened portion.
 2. The laminatedbattery according to claim 1, wherein the notch portion is provided suchthat a width of the surface-roughened portion is partially reduced froman inner side of the outer casing toward an outer side of the outercasing.
 3. The laminated battery according to claim 1, wherein thearithmetic average height of the surface-roughened portion is not lessthan 0.1 μm and not more than 30 μm.
 4. The laminated battery accordingto claim 1, wherein the surface-roughened portion is entirely coveredwith the weld portion.
 5. The laminated battery according to claim 1,wherein part of the surface-roughened portion is exposed to the outsideof the outer casing.
 6. The laminated battery according to claim 1,wherein the electrode terminal is constituted by a clad material inwhich the one end of the electrode terminal is made of a first metal andthe other end of the electrode terminal is made of a second metaldifferent from the first metal.
 7. The laminated battery according toclaim 6, wherein the surface-roughened portion is provided so as tostraddle a boundary between the first metal and the second metal.
 8. Thelaminated battery according to claim 6, wherein a boundary between thefirst metal and the second metal is covered with the weld portion. 9.The laminated battery according to claim 6, wherein one of the firstmetal and the second metal is made of copper or an alloy mainly composedof copper, and a coat layer is provided on a surface of a portion of thecopper or the alloy mainly composed of copper.
 10. The laminated batteryaccording to claim 1, further comprising a resin layer between thesurface-roughened portion and the laminated film in the weld portion.11. The laminated battery according to claim 10, wherein at least partof the resin layer protrudes to the outside of the outer casing.